CO2 transport Flashcards
(48 cards)
Describe the methods of CO2 transport in blood.
CO2 is carried in blood in 3 forms:
1) In physical solution
2) In chemical combination as bicarbonate
3) In chemical combination as carbamino-compounds
Define tidal CO2, mention its normal values
the CO2 given by tissues to 100 cc arterial blood
Value: 3.6 – 4mL/ 100 cc (= ~ 3.7 mL)
CO2 released from tissue metabolism (PCO2 of tissues = …………….)and diffuses to blood (PCO2 of blood = ………………….)
46mmHg , 40mmHg
Describe the changes that occur in blood at tissues - Chloride shift phenomenon
CO2 enters RBCs Inside RBCs, by carbonic anhydrase enzyme (CAE) CO2 & H2O → H2CO3 H2CO3 → H+ and HCO3 ↑ HCO3 → exchange with plasma CL- ↑ CL- inside RBCS → RBCs osmotic forces → suction of H2O to RBCs → increase RBCs volume
HCO3 - CL- passive exchanger:
- HCO3 Moves out by ………………………..
- CL- Moves in by ………………………….
- HCO3 Moves out by concentration gradient
- CL- Moves in by electrical gradient
Mention the Effects of Cl- shift phenomenon in plasma and RBCs
plasma: ↑ HCO3 ↓ Cl- RBCs: ↑ HCO3 ↑ Cl- ↑ osmotic pressure ↑ H2O ↑ Hematocrite value
Most of tidal CO2 is transported as HCO3 because………………………
it is more soluble.
Tidal CO2 doesn’t cause marked pH changes in venous blood (pH: 7.36) than in arterial blood (pH:7.4) because ……………………………………
it is buffered as HCO3 & carbamino compounds
What happens when the carbonic anhydrase inhibitors are used?
↓ Formation of HCO3 inside RBCs
↑ CO2 in plasma
↓ Transport of CO2 from tissues
↑ PCO2 in tissues
Describe the CO2 dissociation curve.
Definition: the relation between PCO2 & CO2 content of blood
Shape: linear
Discuss the importance of Haldane effect at the tissues and at the lung levels
Lungs: ↑ O2 → ↓ affinity of Hb to CO2 & H+ ↓ CO2 & H+ → ↑ affinity of Hb to O2 tissue: ↓ O2 →↑ affinity of Hb to CO2 & H+ ↑ CO2 & H+ → ↓ affinity of Hb to O2
what is the Bohr’s effect?
↑ CO2 & H+→ ↑ release of O2 from Hb to tissues [shift to the right]
what is the Haldane effect?
↑O2 → ↓ affinity of Hb to CO2 & H+
What is hypoxia? Describe the types,
Definition: O2 deficiency at the tissue level types: 1- Hypoxic hypoxia decrease O2 in arterial blood. 2- Anemic hypoxia decrease Hb amount of function in arterial blood 3- Stagnant (ischemic) decrease blood flow to tissues 4- Histotoxic (cytotoxic) inability of tissues to use O2
causes of Hypoxic hypoxia =
↓ Arterial blood PO2
↓ Hb saturation
↓O2 content
1) Extrinsic: ↓ PO2 in inspired air O2 poor air in high altitude Hypoventilation 2) Pulmonary diseases: Hypoventilation Ineffective diffusion 3) Venous to arterial shunt
causes of Anemic hypoxia =
Normal PO2
↓ Blood O2 carrying capacity
↓O2 conten
1) Anemia
2) Abnormal Hb
3) CO poisoning
causes of Stagnant (ischemic) hypoxia =
Normal PO2
Normal O2 content
↓ Tissue blood flow
1) Generalized:
- Shock & Heart failure
2) Localized:
- Vascular spasm or block
causes of Histotoxic (cytotoxic) hypoxia =
Normal PO2
Normal O2 content
↓ Tissue use of O2
1) Cyanide poisoning
2) Beriberi: Vitamin B deficiency
Effects of hypoxia
↓ mental activity drowsiness & coma
↓ work capacity of muscles
Severe hypoxia > Cell death
List the conditions where O2 therapy is of value
hypoxic hypoxia in cases of:
Hypoventilation
Ineffective diffusion
High altitude
List the conditions where O2 therapy has no value
1- Hypoxic hypoxia due to venous-Arterial shunt , 𝑽𝒂\𝑸 mismatching
2- Anemic Hypoxia & abnormal Hb
3- Stagnant hypoxia
Give an account on O2 toxicity and on hyperbaric O2 therapy
O2 toxicity Occur with: 80-100% O2 for 8 hours or more
Hyperbaric O2:
-100% O2 at high pressure
-Its use ↑ the onset of O2 toxicity
Complications of O2 toxicity
1) On lung:
- Irritation of airways
- Sore throat
- Congestion of nose
- ↓ surfactant
2) In premature
- Damage of retina & blindness
- lung Cysts
Define Cyanosis.and where it Appears
Definition: bluish discoloration of skin & mucous membrane due to excess reduced Hb in blood
- Appears in: lips, nail beds, air lobes
